The total combustion of VOC to CO2 and H2O becomes necessary in view of the toxicity and environmental impact of most unburnt VOC. The goal is to minimize the release of VOC into the atmosphere and the forming of CO, which is in turn a toxic component.
The catalysts used most for VOC combustion are:
a) catalysts based on noble metals, which are characterized by a high cost but also by excellent performance in terms of VOC conversion, and operate at temperatures from 200 to 450° C. according to the reactivity of the compound;
b) catalysts based on mixed oxides, typically chromites of copper or of other metals, or barium hexaaluminate, which are characterized by a lower cost but are active in more drastic conditions (temperatures from 400 to 600° C.). This second class of catalysts is also used for catalytic combustors for power generation units. In this case, they operate at temperatures above 900° C.
The types of catalyst used for the combustion of VOC are not free from drawbacks; high cost (for those based on noble metals) and poor activity (for the second class, accordingly requiring operation at higher temperatures, in conditions in which morphologic or structural transformations are facilitated).